Final answer:
Phospholipids are amphipathic molecules with hydrophilic heads and hydrophobic tails, forming the foundation of cellular membranes in a lipid bilayer arrangement.
Step-by-step explanation:
Phospholipids are crucial components of cellular membranes, comprising a hydrophilic (water-loving) head, which contains a phosphate group, and hydrophobic (water-fearing) fatty acid tails. This unique structure makes phospholipids amphipathic molecules, meaning they have both water-soluble and insoluble parts. The amphipathic nature is vital for the formation of cell membranes, where phospholipids line up in a lipid bilayer, with the hydrophobic tails pointing inward, away from water, and the hydrophilic heads facing outward, towards the aqueous environment.